/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.startup;

import java.net.URL;

import org.apache.catalina.util.SchemaResolver;
import org.apache.tomcat.util.digester.Digester;
import org.apache.tomcat.util.digester.RuleSet;

/**
 * Wrapper class around the Digester that hide Digester's initialization details
 * 
 * @author Jean-Francois Arcand
 */
public class DigesterFactory {
	/**
	 * The log.
	 */
	protected static org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory
			.getLog(DigesterFactory.class);

	/**
	 * The XML entiry resolver used by the Digester.
	 */
	private static SchemaResolver schemaResolver;

	/**
	 * Create a <code>Digester</code> parser with no <code>Rule</code>
	 * associated and XML validation turned off.
	 */
	public static Digester newDigester() {
		return newDigester(false, false, null);
	}

	/**
	 * Create a <code>Digester</code> parser with XML validation turned off.
	 * 
	 * @param rule
	 *            an instance of <code>RuleSet</code> used for parsing the xml.
	 */
	public static Digester newDigester(RuleSet rule) {
		return newDigester(false, false, rule);
	}

	/**
	 * Create a <code>Digester</code> parser.
	 * 
	 * @param xmlValidation
	 *            turn on/off xml validation
	 * @param xmlNamespaceAware
	 *            turn on/off namespace validation
	 * @param rule
	 *            an instance of <code>RuleSet</code> used for parsing the xml.
	 */
	public static Digester newDigester(boolean xmlValidation,
			boolean xmlNamespaceAware, RuleSet rule) {
		Digester digester = new Digester();
		digester.setNamespaceAware(xmlNamespaceAware);
		digester.setValidating(xmlValidation);
		digester.setUseContextClassLoader(true);

		if (xmlValidation || xmlNamespaceAware) {
			configureSchema(digester);
		}

		schemaResolver = new SchemaResolver(digester);
		registerLocalSchema();

		digester.setEntityResolver(schemaResolver);
		if (rule != null) {
			digester.addRuleSet(rule);
		}

		return (digester);
	}

	/**
	 * Utilities used to force the parser to use local schema, when available,
	 * instead of the <code>schemaLocation</code> XML element.
	 */
	protected static void registerLocalSchema() {
		// J2EE
		register(Constants.J2eeSchemaResourcePath_14,
				Constants.J2eeSchemaPublicId_14);
		// W3C
		register(Constants.W3cSchemaResourcePath_10,
				Constants.W3cSchemaPublicId_10);
		// JSP
		register(Constants.JspSchemaResourcePath_20,
				Constants.JspSchemaPublicId_20);

		register(Constants.JspSchemaResourcePath_21,
				Constants.JspSchemaPublicId_21);

		// TLD
		register(Constants.TldDtdResourcePath_11, Constants.TldDtdPublicId_11);

		register(Constants.TldDtdResourcePath_12, Constants.TldDtdPublicId_12);

		register(Constants.TldSchemaResourcePath_20,
				Constants.TldSchemaPublicId_20);

		register(Constants.TldSchemaResourcePath_21,
				Constants.TldSchemaPublicId_21);

		// web.xml
		register(Constants.WebDtdResourcePath_22, Constants.WebDtdPublicId_22);

		register(Constants.WebDtdResourcePath_23, Constants.WebDtdPublicId_23);

		register(Constants.WebSchemaResourcePath_24,
				Constants.WebSchemaPublicId_24);

		register(Constants.WebSchemaResourcePath_25,
				Constants.WebSchemaPublicId_25);

		// Web Service
		register(Constants.J2eeWebServiceSchemaResourcePath_11,
				Constants.J2eeWebServiceSchemaPublicId_11);

		register(Constants.J2eeWebServiceClientSchemaResourcePath_11,
				Constants.J2eeWebServiceClientSchemaPublicId_11);

	}

	/**
	 * Load the resource and add it to the resolver.
	 */
	protected static void register(String resourceURL, String resourcePublicId) {
		URL url = DigesterFactory.class.getResource(resourceURL);

		if (url == null) {
			log.warn("Could not get url for " + resourceURL);
		} else {
			schemaResolver.register(resourcePublicId, url.toString());
		}
	}

	/**
	 * Turn on DTD and/or validation (based on the parser implementation)
	 */
	protected static void configureSchema(Digester digester) {
		URL url = DigesterFactory.class
				.getResource(Constants.WebSchemaResourcePath_24);

		if (url == null) {
			log.error("Could not get url for "
					+ Constants.WebSchemaResourcePath_24);
		} else {
			digester.setSchema(url.toString());
		}
	}
}
